Mikhail Khodorkovsky, Russia's most famous political prisoner, has said he harbours no ambition to challenge Vladimir Putin and go into politics, adding that he will not return to Russia while he faces the prospect of re-arrest there.

Speaking 36 hours after he was freed from a Russian prison and flown to Berlin, Khodorkovsky said he had not had time to decide where he will live. He immediately ruled out a political career, or a return to business, but said he would be a "public figure".

Asked whether he felt personal gratitude to Putin, who signed a decree on Friday pardoning him, he said: "It's very hard for me to say I'm grateful to him. I've thought for a long time about what words I should use. I'm glad of his decision."

Khodorkovsky met a small group of western journalists, including the Guardian, on Sunday at the Checkpoint Charlie Museum in Berlin – a symbolic venue. Dressed in a blue suit, he looked relaxed, smiling, and answered questions without rancour. He even managed a few jokes.

Asked how he had changed in prison camp, his home for the past 10 years, he replied: "The biggest change is that I'm 10 years older." Once Russia's richest man, Khodorkovsky said he did not know how much money he had left – most of his assets were seized – adding: "I won't be buying a football club."

Khodorkovsky was arrested in 2003 after financing opposition political parties. His imprisonment was widely regarded as a political punishment by the Kremlin, and by Putin personally. The tycoon was convicted twice on fraud and tax evasion charges. His oil company, Yukos, was broken up, sold off, and given to state oil company Rosneft, headed by Putin's ally Igor Sechin. On Sunday, he described the cases against him as "phantasmagoric".

Khodorkovsky said his refusal to enter politics would not stop him from campaigning for the release of his friend and Yukos colleague Platon Lebedev. Lebedev, his co-defendant in two trials, remains in jail. The former oligarch said he would not go back to Russia while a civil claim arising from his first trial still hangs over him. If he were to go back he could be re-arrested at any moment, he said.

The oil tycoon said the idea of a pardon was first floated back in 2008 by President Dmitry Medvedev. But he refused to apply for one because this would have meant admitting his guilt – potentially implicating his Yukos colleagues, who might then face extradition to Russia, he said.

Then on 12 November his lawyers brought a proposal from former German foreign minister Hans-Dietrich Genscher. Genscher, who had held secret talks with Putin, said he should write to Russia's president asking for pardon. "I looked at it. There was no demand I recognise my guilt," Khodorkovsky recalled.

The prison governor woke him at 2am on Friday with the pardon and asked if he wanted to leave for Germany. "They didn't offer me an alternative," he said. Khodorkovsky knew his mother was being treated in a Berlin clinic. He was flown to St Petersburg in a helicopter before being whisked out of the country and into exile by private jet.

His exit from Russia was "in the best tradition of the 1970s", he said, a reference to the practice of bundling Soviet dissidents such as Alexandr Solzhenitsyn out of the country. On Saturday, Khodorkovsky was reunited with his family – his parents Marina and Boris, who flew in from Moscow, and his son Pavel from New York. His wife Inna is wrapping up paperwork in Moscow and will join him soon.

Asked whether he had missed them, Khodorkovsky paused, struggled for words, then said: "I was only allowed family visits for four years out of the 10, and then only for a few minutes once a month." He said he was unable to answer many questions – such as whether foreigners should now invest in Russia – because he was deprived of proper information.

He told the Guardian the forthcoming Sochi Olympics may have been a factor in his sudden release. More broadly, he added: "I think it [my release] is a symbol that the Russian government and Putin personally are seriously worried about the country's image." But his freedom didn't, in his view, signify Russia was heading for "deep" or meaningful reforms, he said.

The tycoon suggested there was not likely to be a change in Russia's leadership soon. "Putin is healthy", he observed. "He could carry on for a long time." Russia's opposition remained weak, he said. The core problem was that political awareness within Russian society was still feeble, he said – though better than 10 years ago when he went to jail.